In the earlier international Patent Application WO 95/08019 A1, which is not a prior publication, a device is proposed for operating an installation specifically for the production of deinked pulp. The installation includes at least one waste paper preparation means, downstream of which a paper machine or at least one dewatering machine is connected. In this case, measuring devices for registering spectral and/or physical characteristic values of the waste paper suspension are already used. Furthermore, regulating or controlling devices are used there for the operating means of the waste paper preparation means. There is also at least one state analyser, designed in the form of one or more parallel neural networks, for the waste paper suspension. The analyzer, by means of the characteristic values of the measuring device, supplies controlled variables for process management to the regulating or controlling devices of the operating means for the waste paper preparation means.
In the case of the device described above for the production of deinked pulp, using as great a proportion as possible of waste paper, there is in particular the problem that the quality of waste paper introduced into the installation fluctuates severely. For example, there can be, in the respective mixture of waste paper, sharply variable proportions of, for example, coloured illustrated paper, gray newsprint, white paper, contaminated paper, old books, for example with adhesive residues, such as telephone directories, cartons, packages, coated papers and contaminations of all types. The device previously described in the earlier Patent Application solves these problems in a satisfactory manner for the waste paper preparation means.
EP-A-0,137,696 discloses a method and an associated device for registering the water content of a paper web during production, in which, via an optical infrared measurement, use is made of the fact that water has an absorption band at 1.94 .mu.m. To this end, a measuring channel and a reference channel having a different wavelength than the water absorption band is used. In addition, U.S. Pat. No. 5,282,131 discloses a system for regulating a pulp washing plant, in which a neuron network is employed to verify predictable process parameters. In the case of both of these documents, therefore, only some aspects of paper production are addressed.